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void setup()
{
size (500, 500);
background (0);
fill (255, 255, 0);
noStroke();
ellipse (0, 0, 150, 150);
stroke (255);
strokeWeight (4);
line (0, 490, 500, 490);
line (0, 470, 500, 470);
line (0, 440, 500, 440);
line (0, 400, 500, 400);
line (0, 350, 500, 350);
line (0, 300, 500, 300);
line (0, 240, 500, 240);
line (0, 160, 500, 160);
line (0, 80, 500, 80);
}
void draw()
{
float winkel = map (mouseX, 0, 250, 0, 2*PI);
rotate (winkel);
stroke (255);
strokeWeight (2);
line (0, 240, 500, 240);
}